The instant invention relates to a yarn draw-off pipe, as well to a holder for a yarn draw-off pipe on the housing of a spin box of a rotor spinning machine.
An open-end spinning device in which a draw-off nozzle for the withdrawal of the spun yarn is provided on the cover of the rotor housing and in which a yarn draw-off pipe is connected after the yarn draw-off nozzle is known from EP 0200 092. The yarn draw-off pipe is pressed axially against the yarn draw-off nozzle by means of a spring which bears upon it on its side away from the yarn draw-off nozzle.
A cover of an open-end rotor spinning device equipped with a yarn draw-off nozzle on its side towards the rotor and with an opening on its side away from the rotor into which a yarn draw-off pipe extends, and whereby the yarn can be guided through the draw-off pipe out of the rotor housing, is known from the German patent application P 41 31 665.7. The yarn draw-off pipe is held in its axial position similarly as in EP 0200 092 B1, by means of an elastic element which holds the yarn draw-off pipe with pre-stress in its axial position. The elastic element in this case is made in the form of a leaf spring which can be lifted and swivelled to remove the yarn draw-off pipe. This type of design of a yarn draw-off pipe and its attachment on the rotor cover has the disadvantage that when the yarn draw-off pipe is to be replaced, the leaf spring must first be swivelled away before the yarn draw-off pipe can be removed and replaced by a new one. This a disadvantage insofar as access is difficult through a housing cover to the back of the rotor cover. The operator must therefore lift the spring with one hand and pull out the yarn draw-off pipe or install a new yarn draw-off pipe with the other hand.
The holder of the yarn draw-off pipe is made in the form of a pipe-shaped element in this case, which is attached to a mounting plate to which the cover of the spin box is mounted. The holder extends axially into a bore of the rotor cover and guides the yarn draw-off pipe radially while it is held axially by a leaf spring. The holder for the yarn draw-off pipe may also be mounted on the rotor cover itself or be an integral part thereof as is shown in EP 0200 092 B1.
A yarn draw-off pipe with a surface for the bearing of an elastic element is known from DE-OS 25 38 258. The elastic element is used here to push the yarn draw-off pipe out of its holder. For disassembly, a safety element must be unscrewed for this. In another design the safety element is spring-loaded.